Systems and methods for guiding surgical tools

ABSTRACT

The present disclosure generally relates to systems and methods for guiding surgical tools to a surgical site, and more particularly, to systems and methods for guiding a tool sheath of a delivery system to a surgical site such as a location in a subject&#39;s brain and associated surgical procedures.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/831,983, filed Apr. 10, 2019, the entirety of whichis incorporated herein by reference.

FIELD

The present disclosure generally relates to systems and methods forguiding surgical tools to a surgical site, and more particularly, tosystems and methods for guiding a tool sheath of a delivery system to asurgical site such as a location in a subject's brain and associatedsurgical procedures.

BACKGROUND

Currently, deep seated gliomas and brain lesions are treated with usingstraight trajectory laser ablations through a procedure called LaserInterstitial Thermal Therapy (LITT), which is a minimally invasivetreatment option for brain tumors. Neurosurgeons plan out their straighttrajectories from MRI scans and use surgical navigation software toposition the most efficient way to eliminate the tumor. A 3.2 mmdiameter burr hole is created to allow a fiber-optic probe to follow thepreset trajectory. A threaded plastic bone anchor is then screwed intothe trajectory of the lesion. The fiber-optic probe is then secured tothe anchor at the correct depth using navigation software and MRIguidance. Thermal energy by a photo-thermal process from the fiber-opticprobe is emitted to ablate the tumor. MRI images are taken to view theeffect of the thermography. The ventriculoperitoneal (VP) shunt 1 shownin FIG. 1 is another way for neurosurgeons to access regions of thebrain.

There are cases where thermal ablation is not fully effective withdamaging the entire tumor. With MRI scans taken, the thermal ablationimages will show portions of the tumor unaffected by the ablation. Withheat radiating in a spherical or cylindrical shape, tumors often do notresemble these shapes for optimal ablation due to their complexgeometries. The use of straight tools and trajectories during LITTlimits the ability for the thermal ablation to reach to tumor margins.The neurosurgeon is left with the option to repeat the ablationapplication to the tumor with another burr hole to access the desiredregion. This increases the time of the operation and risk of infectionand complications. Healthy brain tissue is also at risk if multipletrajectories are created for ablations.

Although there is extensive work in needle-based neurosurgery, many ofthese systems are also limited to using straight trajectories underimage guidance. There is a body of research on steerable medicaldevices, including needles and continuum robots such as active cannulas.Both steerable needles and active cannulas have small form factors, arebiocompatible, and offer methods for reaching targets along a curvedpath. Active cannulas 2 (FIG. 2) provide dexterous motion due to theirelastic, precurved concentric telescoping tubes. The active cannula 2 istypically comprised of multiple, concentric, needle-like tubes, at leastone of which is precurved and superelastic, whose properties areselected a priori based on task requirements. These designs often leadto intricate, complex configurations, sometimes consisting of three ormore tubes. The active cannula 2 shown in FIG. 2 displays a concentrictube design, which of four superelastic Nitinol tubes that can rotateand translate with respect to one another. Alternate approaches alsoexist such as a two tube design, where additional tubes could be addedor removed during surgery for hemorrhage evacuation. There remains aneed for new systems and methods to access surgical sites, particularlysurgical sites within the brain, that are not limited to straighttrajectories.

SUMMARY

Various aspects of the present disclosure relate to methods foraccessing a surgical site in a subject. In some embodiments, thesemethods comprise advancing a distal end of a delivery system throughbody tissue of the subject to position the distal end of the deliverysystem in the body tissue and a proximal end of the delivery systemoutside the body tissue. The delivery system is configured to guide asurgical tool to the surgical site. The delivery system includes adelivery sleeve having a longitudinal axis extending between proximaland distal ends of the delivery system, a tool sheath movably disposedlongitudinally within the delivery sleeve, and a first guide movablydisposed longitudinally within the tool sheath. The methods includeguiding the distal end of the delivery system to the surgical site bylongitudinally moving the first guide and the tool sheath relative tothe delivery sleeve. The methods include retracting the first guideproximally through the tool sheath such that the distal end of thedelivery system is defined by the distal end of the tool sheath.

Other aspects of the disclosure relate to methods of performing asurgical procedure in a subject's brain. In various embodiments, thesemethods comprise accessing the surgical site within the subject's brainaccording to a method as described herein. The methods also includeadvancing a surgical tool distally though the tool sheath to positionthe surgical tool at the surgical site and operating the surgical tool.

Further aspects of the disclosure relate to delivery systems for guidinga surgical tool to a surgical site. In various embodiments, the deliverysystems comprise a delivery sleeve having a longitudinal axis andproximal and distal ends spaced apart from one another along thelongitudinal axis. The delivery sleeve is configured to be inserted intothe body tissue of a subject. A tool sheath is movably disposedlongitudinally within the delivery sleeve. The tool sheath defines alumen configured to receive the surgical tool. A first guide is movablydisposed longitudinally in the lumen of the tool sheath. The first guideis deformable and has a generally curved shape when the first guide isnot deformed. The first guide and tool sheath are configured to be moveddistal of the delivery sleeve so that the first guide can guide a distalend of the tool sheath to the surgical site. The first guide is deformedwhen the first guide is disposed within the delivery sleeve and at leasta portion of the first guide has a generally curved shape when the firstguide is moved distally through the distal end of the delivery sleeve.The tool sheath is flexible and generally conforms to the shape of thefirst guide.

Further aspects of the disclosure relate to delivery systems for guidinga surgical tool to a surgical site. In various embodiments, the deliverysystems comprise a first guide having a longitudinal axis and proximaland distal ends spaced apart from one another along the longitudinalaxis. The first guide is configured to be inserted into the body tissueof a subject. The first guide defines a lumen extending between theproximal and distal ends. The first guide is deformable and has agenerally curved shape when the first guide is not deformed. A secondguide is movably disposed in the lumen of the first guide. The secondguide is deformable and has a generally curved shape when the secondguide is not deformed. The longitudinal axis has a first shape when thefirst and second guides are disposed relative to one another in a firstconfiguration and a second shape different than the first shape when thefirst and second guides are disposed relative to one another in a secondconfiguration.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an illustration of complex ventricle targeting for shuntplacement;

FIG. 2 is an image of an active cannula system with minimally invasiveconcentric tubes;

FIG. 3 is an illustration of inaccessible regions of surgical site of asubject's brain using straight trajectory laser ablations.

FIG. 4 is a front perspective of a delivery system according to oneembodiment of the present disclosure, the delivery system in a startposition;

FIG. 5 is a cross-section of the delivery system taken through line 5-5of FIG. 4;

FIG. 6 is a front perspective of the delivery system in an end position;

FIG. 7 is a rear perspective of the delivery system in the end position;

FIG. 8 is a cross-section of the delivery system taken through line 8-8of FIG. 6;

FIG. 9 is a front perspective of the delivery system with a driveassembly thereof removed;

FIG. 10 is an enlarged, fragmentary cross-sectional view of a deliverysleeve, a tool sheath, a first guide and a second guide of the deliverysystem;

FIG. 11 is a fragmentary perspective of the delivery sleeve, the toolsheath, the first guide and the second guide;

FIGS. 12A-12C are fragmentary perspectives of the delivery sleeve, thetool sheath, the first guide and the second guide illustrating thelongitudinal movement of these components relative to one another;

FIG. 13 is an illustration of the first and second guides in a firstconfiguration to create a straight trajectory;

FIG. 14 is an illustration of the first and second guides in a secondconfiguration to create a curved trajectory;

FIG. 15 is an exploded view of the drive assembly;

FIG. 16 is a rear perspective of a plunger of the drive assembly in aninsertion position;

FIG. 17 is a rear perspective of the plunger in a withdrawal position;

FIG. 18 is an exploded view of the delivery system; and

FIG. 19 is an illustration of the delivery system guiding a surgicaltool to a surgical site.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION

In general, the systems and methods described herein are for guiding orsteering existing straight, but flexible surgical tools T to a surgicalsite S. The surgical site S may be located within any portion of thesubject's body, such as the brain B (FIG. 3). The delivery systems(e.g., curved port delivery system, port delivery system, cannuladelivery system) as described herein enables surgical tools T thataren't inherently steerable, to be able to be steered to desiredoff-axis targets. Moreover, the delivery systems arebiocompatible/MRI-compatible and retains surgical workflow of existingprocedures, while adding enhanced dexterity when needed.

Moreover, the delivery systems enable existing imaging technologies toimage the surgical tool T and the surgical site S without interferingwith the image. It has been observed that existing cannula systems usingNitinol tubes interfere with thermometry readings when the Nitinol istoo proximate to the laser tip (e.g., surgical tool). For example,Nitinol in these existing cannula systems causes imaging artifacts(e.g., distortions) during MRI's and thermometry artifacts during LITT.Nitinol is a nickel-titanium alloy. Existing cannula systems usingNitinol tubes to guide the laser tip to the surgical site are notsufficiently thermometry compatible for accurate tip (e.g., probe)placement because of the heat generated during LITT. As explained inmore detail below, because the delivery system described herein may usecomponents containing Nitinol to guide a tool sheath to the surgicalsite, but then be subsequently removed from the surgical site S afterthe placement of a tool sheath, the delivery system is able to guide asurgical tool T to a surgical site without interfering or distortingimages taken of the surgical site and tool thereat. Such a deliverysystem can be used in neurosurgical applications where imaging accuracyand in the case of tumor ablation, thermometry accuracy, are paramount,such as LITT.

Considering that many neurosurgical laser ablation catheters andsurgical probes (which are types of surgical tools T) are alreadyinherently flexible, MRI-compatible, biocompatible, andthermometry-compatible, the end objective primarily sits in theirability to be steered to a targeted location. As opposed tosignificantly modifying these existing tools (or designing entirely newones) to be steerable, the delivery system enables these flexiblesurgical instruments T to be steered or guided to desired locations(e.g., surgical site S). In other words, the delivery systems providesteerability to surgical tools T that are otherwise not steerable. Thisallows the surgical procedure, such as LITT, to be conducted by startingwith a straight, flexible surgical tool T, as it normally done. When thesurgeon reaches a point during the procedure where more dexterity isneeded, one of the delivery systems according to the present disclosureis used. The delivery systems enable the surgeon to deploy abiocompatible, MRI-compatible, and thermometry-compatible plastic port(broadly, a tool sheath) along a desired curved trajectory to thesurgical site S. This port serves as a guide to “steer” the existingflexible tools T used in the surgical procedure to new targets that wereotherwise unreachable using the straight surgical tool (FIGS. 3 and 19).The delivery systems allow existing surgical tools T to be operatednormally but now along a curved trajectory. Once the targeted locationsS have been reached, the surgical tools T are removed from the port, andthe port is retracted out via the same deployment system. The procedurethen continues as it normally would. Using the delivery systems, asdescribed herein, provide several advantages such as (1) the surgicaltools T themselves would not be significantly altered and would maintaincurrent standards of functionality, clearance, and compatibility; (2)the system supports a number of different surgical tools within a givensize restriction, making it a more universal solution; (3) the surgicalworkflow would largely remain consistent; and (4) enhanced dexterity andcapability is still provided to the surgeon for treatment, affording thepotential for better patient outcomes.

The delivery systems as disclosed herein may act as part of a touch uptool to ablate complex geometrically shaped tumors M that otherwisewould not be ablated with a normal straight trajectory surgical tools T(FIG. 3), such as a fiber-optic probe or laser ablations. After thermalablation is applied to the tumor M, neurosurgeons can use MRI toevaluate how effective the surgical tool T (e.g., fiber-optic probe)was. If it is determined that significant portions of the tumor M remainat the surgical site S, the delivery system can deliver a port or toolsheath into unique locations using the single burr hole used in the LITTprocedure (FIG. 19). Upon the placement of the curved port or toolsheath in the brain B, the fiber-optic probe T follows the created pathof the port or tool sheath. This enables neurosurgeons to reach uniquelocations of the tumor M outside the range of the straight trajectoriesfirst used (FIGS. 3 and 19). With the ability to reach more areas, lowerheating profiles can be used decreasing the risk of harming healthybrain B tissue.

Typically, the tool sheath (as described in more detail below) isconstructed of a polymer. In various embodiments, the polymer comprisesa polyamide, such as a synthetic polyamide (e.g., various nylonsincluding nylon 6,6 and nylon 6), polyvinyl chloride (PVC),polycaprolactone (PCL), polydioxanone (PDO), or a fluoropolymer.Fluoropolymers include, for example, polytetrafluoroethylene (PTFE),fluorinated ethylene-propylene (FEP), perfluoroalkoxy resin (PFE, acopolymer of tetrafluoroethylene and perfluorovinylethers),ethylene-tetrafluoroethylene copolymer (ETFE),polychlorotrifluoroethylene (PCTFE), ethylene-chloro-trifluoroethylenecopolymer (ECTFE), polyvinylidene fluoride (PVDF), and polyvinylfluoride (PVF). Preferably the fluoropolymer is PTFE.

Having explained some of the general features of the present disclosure,more detailed embodiments of the delivery system will now be described.

Referring to FIGS. 4-18, one embodiment of a delivery system for guidinga surgical tool T to a surgical site within the body tissue is generallyindicated by reference numeral 100. The delivery system 100 may includean elongate body or delivery sleeve 102 (FIG. 10) having a longitudinalaxis LA and proximal and distal ends spaced apart from one another alongthe longitudinal axis. The delivery sleeve 102 is configured to beinserted into the body tissue (e.g., brain B) of a subject. The deliverysleeve is generally straight and rigid. The delivery sleeve 102 definesa delivery sleeve lumen 104 extending along the longitudinal axis LAbetween the proximal and distal ends. The delivery system 100 alsoincludes a tool sheath 106 (as described above) movably disposedlongitudinally within the delivery sleeve 102 (e.g., the lumen 104thereof). For reasons that will become apparent, the length of thedelivery sleeve 102 is less than the length of the tool sheath 106. Thetool sheath 106 defines a tool sheath lumen 108 configured to receivethe surgical tool S. The tool sheath lumen 108 extends between proximaland distal ends 109, 111 of the tool sheath 106.

The delivery system 100 also includes a first guide 110 (e.g., a firsttube) movably disposed in the lumen 108 of the tool sheath 106. Thefirst guide 110 may move longitudinally and/or rotationally within thetool sheath 106. The first guide 110 may define a first guide lumen 112extending between the proximal and distal ends of the first guide. Thefirst guide lumen 112 may extend between proximal and distal ends of thefirst guide 110. The first guide 110 is deformable and has a generallycurved shape when the first guide is not deformed (FIGS. 13 and 14).Preferably, a distal portion of the first guide 110 is curved when thefirst guide is unrestricted (e.g., not deformed). In one embodiment, thedistal portion is about the distal third of the length of the firstguide 110. The first guide 110 and tool sheath 106 are configured to bemoved distal of the delivery sleeve 102 so that the first guide canguide the distal end 109 of the tool sheath 106 to the surgical site S(e.g., a particular location within the surgical site). The first guide110 is deformed when the first guide is disposed within the deliverysleeve 102 (because the delivery sleeve is generally rigid). Inparticular, the first guide 110 is generally straight when disposedwithin the delivery sleeve 102. At least a portion of the first guide110 (e.g., the portion of the first guide distal of the delivery sleeve102) has a generally curved shape when the first guide is moved (e.g.,advanced) distally through the distal end of the delivery sleeve. Thisis because the portion of the first guide 110 outside of the deliverysleeve 102 is no longer constrained (e.g., deforming) by the deliverysleeve, permitting the portion of the first guide outside the deliverysleeve to return to its nature, curved state. The tool sheath 106 isflexible and generally conforms to the shape of the first guide 110.Thus, the portion of the tool sheath 106 disposed outside the deliverysleeve 102 that houses the portion of the first guide 110 which iscurved (because it is also outside the delivery sleeve), also becomescurved.

The delivery system 100 may also include a second guide 114 (e.g., asecond tube) movably disposed longitudinally within the first guide 110(e.g., the lumen 112 thereof). The second guide 114 operates in the samemanner as the first guide 110. The second guide 114 is deformable andhas a generally curved shape when the second guide is not deformed. Thesecond guide 114 may have the same or different curve as the first guide110. Preferably, a distal portion of the second guide 114 is curved whenthe second guide is unrestricted (e.g., not deformed). In oneembodiment, the distal portion is about the distal third of the lengthof the second guide 114. The second guide 114 is deformed when thesecond guide is disposed within the delivery sleeve 102. Other ways ofdeforming the first and second guides 110, 114 are within the scope ofthe present disclosure. For example, the first and second guides 110,114 can deform each other as discussed in more detail below. The firstand second guides 110, 114 and tool sheath 106 are configured to bemoved distal of the distal end of the delivery sleeve 102 so that thefirst and second guides can guide the distal end 109 of the tool sheathto the surgical site S. The first and/or second guides 110, 114 serve asthe steering backbone of the tool sheath 106 (broadly, the deliverysystem 100) and create the non-sweeping, curved trajectories that guidethe distal end of the delivery system (e.g., the distal end 109 of thetool sheath) to a desired location within the surgical site S of thesubject's brain B. In this embodiment, the delivery system 100 may notinclude the delivery sleeve 102 because the interaction between thefirst and second guides 110, 114 is able to straighten and curve thelongitudinal axis LA, as discussed in more detail below. The first andsecond guides 110, 114 are generally aligned with (e.g., define) thelongitudinal axis LA.

The first and second guides 110, 114 are configured to move at least oneof longitudinally and rotationally relative to one another to change therelative shapes of the first and second guides (e.g., the longitudinalaxis LA). In this manner, by selectively positioning, longitudinally androtationally, the first and second guides 110, 114 relative to oneanother, the particular shape defined by the first and second guides canchange to guide the tool sheath 106 to different locations at thesurgical site S. In other words, because both the first and secondguides 110, 114 are elastic and curved in an undeformed state,positioning the first and second guides relative to one another changesthe curved trajectory or path (e.g., the longitudinal axis LA) definedby the combination of or interaction between the first and secondguides. Specifically, the longitudinal axis LA has a first shape (e.g.,straight) when the first and second guides 110, 114 are disposedrelative to one another in a first configuration (FIGS. 4, 5 and 13) anda second shape (e.g., curved) different than the first shape when thefirst and second guides are disposed relative to one another in a secondconfiguration (FIGS. 6-8 and 14). In one embodiment, as shown in FIG.13, positioning the first and second guides 110, 114 in the firstconfiguration such that the guides are 180 degrees relative to oneanother (such the curves are curving in opposite directions) results inthe first and second guides (e.g., the longitudinal axis LA) having agenerally straight shape (e.g., the elastic forces of the guidesgenerally offset one another). Similarly, as shown in FIG. 14,positioning the first and second guides 110, 114 relative to one anotherin a second configuration (different than the first) results in thefirst and second guides having a generally curved shape—the degree ofthe curve becoming larger as the first and second guides are rotatedinto alignment with the maximum degree of curvature occurring with thecurves of the first and second guides are aligned. It is understood thesecond configuration of the first and second guides 110, 114 may begenerally any position of the first and second guides relative to oneanother to get any desired degree of curvature between 0 (e.g.,straight) and the maximum degree of curvature (including the maximumdegree of curvature). Thus, as will become apparent, a surgeon canrotate the first and second guides 110, 114 relative to one another tocreate the necessary trajectory to reach other locations of the surgicalsite S (e.g., locations out of reach of a straight line). When thedelivery system 100 includes the second guide 114, the tool sheath 106generally conforms to the shapes of the first and second guides (e.g.,conforms to the path or longitudinal axis LA defined by the first andsecond guides and the interactions thereof).

In this embodiment, the first guide 110 (and second guide 114 whenincluded) of the delivery system 100 is configured to be removed fromthe lumen 108 of the tool sheath 106 to permit the surgical tool T to beinserted into the lumen. Thus, once the first and/or second guides 110,114 have positioned the tool sheath 106 at the surgical site S, thefirst and/or second guides are removed. In one embodiment, the first andsecond guides 110, 114 comprise (e.g., are made of) a nickel-titaniumshape memory allow such as Nitinol. As mentioned above, Nitinol caninterfere with imaging of the surgical site S. But by removing the firstand second guides 110, 114 from the tool sheath 106 once the tool sheathhas been positioned at the desired location at the surgical site S, nocomponents of the delivery system 100 containing Nitinol are positionedat the surgical site when the surgical tool is at the surgicalsite—allowing clear images to be generated of the surgical tool at thesurgical site. Accordingly, the tool sheath 106 is preferably free ofNitinol or other materials that would interfere with imaging thesurgical site S. In some embodiments, the first and second guides 110,114 may also comprise (e.g., be constructed of) other materials such asone or more polymers. For example, such polymers include polyamides,such as synthetic polyamides (e.g., various nylons including nylon 6,6and nylon 6), polyvinyl chloride (PVC), polycaprolactone (PCL),polydioxanone (PDO), or a fluoropolymer. Fluoropolymers include, forexample, polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene(FEP), perfluoroalkoxy resin (PFE, a copolymer of tetrafluoroethyleneand perfluorovinylethers), ethylene-tetrafluoroethylene copolymer(ETFE), polychlorotrifluoroethylene (PCTFE),ethylene-chloro-trifluoroethylene copolymer (ECTFE), polyvinylidenefluoride (PVDF), and polyvinyl fluoride (PVF). Preferably thefluoropolymer is PTFE. Such biocompatible polymers do not interfere withthe imaging of the surgical site S, permitting the first and secondguides 110, 114 to remain at the surgical site as described in moredetail below.

The delivery system 100 leverages the first and/or second guides 110,114 to guide the distal end of the delivery system to the surgical siteS. In one embodiment, the first and second guides 110, 114 areneedle-sized, tentacle-like tubes. As mentioned above, in oneembodiment, these tubes 110, 114 are pre-curved, superelastic Nitinol,enabling them to telescope in and out of one another and rotate axiallywith respect to one another. These types of Nitinol tubes 110, 114 arewell-suited for neurosurgical applications, with advantages including(1) the ability to traverse along straight or curved paths in afollow-the-leader style—meaning they can be deployed and retracted alongthe same path and cause little to no “sweeping” of tissue, (2) they havea small size (e.g., form factor), with some as small as 0.5 mm in outerdiameter, and (3) they are biocompatible and are limited MRI-compatible.

As mentioned above, the disadvantage to the existing systems that useNitinol is that Nitinol is not well-suited for thermometry, and whileMRI-compatible up to a certain point, still leaves some artifacts inimaging. However, plastic materials do not possess such disadvantages.However, most plastics do not possess the inherent superelastic natureof Nitinol, which is why Nitinol is particularly well suited forgenerating paths for surgical tools T. The delivery systems 100 of thepresent disclosure provide the advantages of each of these components,using the Nitinol-based guides 110, 114 for delivery of a plastic toolsheath 106, which then becomes the primary channel for deployingsurgical tools T once the guides are retracted (leaving the tool sheathas the only component of the delivery system at the surgical site). Thisapproach leverages the advantages of both systems to providesteerability to the surgical site S via the guides 110, 114 and imagingcharacteristics of the plastic tool sheath 106.

The delivery system 100 generally uses a three tube design: (1) astraight outer delivery sleeve 102; (2) first and/or second guides 110,114; and (3) the plastic tool sheath 106. In one embodiment, the firstguide 110 has an outer diameter of about 2.311 mm and an inner (e.g.,lumen 112) diameter of about 2.108 mm, the second guide 114 has an outerdiameter of about 1.854 mm and an inner (e.g., lumen) diameter of about1.702 mm, and the tool sheath 106 has an outer diameter of about 3.97 mmand an inner (e.g., lumen 108) diameter of about 2.38 mm. This deliverysystem 100 provides sufficient dexterity needed for retraction anddeployment without the complexity that comes with a larger number oftubes. The straight outer delivery sleeve 102 provides a translationaldegree of freedom that enables easy control of the depth at which curvedtrajectory begins. In operation, the tool sheath 106, the first guide110 and the second guide 114 extend through the delivery sleeve 102 toreach the surgical site S. The delivery system 100 can be mounted ontoan existing clinical setup and would be positioned using a linear slideor track, as described in more detail below. The first and second guides110 are pre-curved and placed concentrically inside the straight outerdelivery sleeve 102, enabling curved trajectories to be achieved upondeployment from the delivery sleeve. The first and second guides 110,114 may achieve various different curved trajectories by the interactionof forces from their pre-curvatures. As shown in FIGS. 13 and 14, thetwo guides 110, 114 can achieve straight and curved trajectories bytranslating and rotating the two guides in and out of phase with oneanother.

The delivery system 100 may also include a drive assembly, generallyindicated at 120, configured to be engaged by a surgeon or operator tocontrol the operation of the delivery system. The drive assembly 120 isoperatively connected to the delivery sleeve 102, the tool sheath 106and the first guide 110 and is configured to move the delivery sleeve,the tool sheath and the first guide into the body tissue of the subject.The drive assembly 120 is configured to move the delivery sleeve 102,the tool sheath 106 and the first guide 110 together into the bodytissue of the subject. In addition, the drive assembly 120 is configuredto move each of the delivery sleeve 102, the tool sheath 106 and thefirst guide 110 relative to one another. For example, the drive assembly120 is configured to move the tool sheath 106 relative to the deliverysleeve 102. The drive assembly 120 is also configured to rotate thefirst guide 110 relative to the delivery sleeve 102 and the tool sheath106. If included, the drive assembly 120 is also configured to rotatethe second guide 114 relative to the delivery sleeve 102, the toolsheath 106 and the first guide 110.

In one embodiment, the drive assembly 120 may permit the surgeon toindividually control the longitudinal and/or rotational position of thedelivery sleeve 102, the tool sheath 106, the first guide 110 and thesecond guide 114. The drive system 120 may include individual actuatorsoperatively connected to each of the delivery sleeve 102, the toolsheath 106, the first guide 110 and second guide 114 to control themovement (e.g., longitudinal and/or rotational) thereof. For example,the actuator operatively connected to the delivery sleeve 102 can beused to move the delivery sleeve proximally and distally along thelongitudinal axis LA. The actuator operatively connected to the toolsheath 106 can be used to move the tool sheath proximally and distallyrelative to the delivery sleeve 102 and along the longitudinal axis LA.The actuator operatively connected to the first guide 110 can be used tomove the first guide proximally and distally relative to the deliverysleeve 102 and/or the tool sheath 106 (e.g., the longitudinal axis LA)and/or rotate the first guide relative to the delivery sleeve and/or thetool sheath. The actuator operatively connected to the second guide 114can be used to move the second guide proximally and distally relative tothe delivery sleeve 102, the tool sheath 106 and/or the first guide 110(e.g., the longitudinal axis LA) and/or rotate the second guide relativeto the delivery sleeve, the tool sheath and/or first guide. Otherconfigurations of the drive assembly 120 are within the scope of thepresent disclosure. For example, two or more of the actuators may belongitudinally and/or rotatably coupled together such that the two ormore actuators move together (e.g., simultaneously). For example, theactuators of the tool sheath 106, the first guide 110 and the secondguide 114 may be longitudinally coupled together such that thesecomponents move together along the longitudinal axis LA. Moreover, thetwo or more actuators may be releasable coupled together, such that whenconnected the two or more actuators move together and when disconnected,the two or more actuators move independently.

In one embodiment, a single actuator is operatively connected to boththe first and second guides 110, 114 to move the first and second guidesrelative to one another, the delivery sleeve 102 and/or the tool sheath106. In this embodiment, the single actuator may also be operativelyconnected to the both the first and second guides 110, 114 to rotate thefirst and second guide relative to one another, the delivery sleeve 102and/or the tool sheath 106. For example, the single actuator may beoperatively connected to the first and second guides 110, 114 such thatmovement of the single actuator rotates the first guide in one direction(e.g., clockwise) and the second guide in the opposite direction (e.g.,counter-clockwise) at the same time. All the actuators may be mounted ona track that allows each actuator (collectively or individually) to movealong the track. The actuators may also be selectively lockable inposition on the track.

Referring to FIGS. 4-9 and 15-18, one embodiment of the drive assembly120 is generally shown. In this embodiment, the drive assembly 120enables the translation of the tool sheath 106, the first guide 110 andthe second guide 114 along the longitudinal axis LA and the rotations ofthe first and second guides about the longitudinal axis to occursimultaneously and through the use of a single actuator. The driveassembly 120 includes a rail or track 122 on which the delivery sleeve102, the tool sheath 106 and the first and second guides 110, 114 aremovably mounted. The track 122 allows the delivery sleeve 102, the toolsheath 106 and the first and second guides 110, 114 to move along thelongitudinal axis LA to control the overall depth of the delivery system100 in the tissue of the subject. The track 122 is generally parallel tothe longitudinal axis LA. The drive assembly 120 includes a tool sheathmount 124. The tool sheath mount 124 is slidably mounted on the track122 and may include a first retainer 126 (e.g., a fastener) used tosecure the tool sheath mount in position on the track. The tool sheathmount 124 is coupled to and supports the tool sheath 106. The toolsheath mount 124 may include a tool sheath retainer 128 (e.g., a setscrew) used to releasably couple the tool sheath 106 to the tool sheathmount 124. The drive assembly 120 may also include a delivery sleevemount (not shown), which is generally identical to the tool sheath mount124. The delivery sleeve mount is mounted distally of the tool sheathmount 124 on the track 122.

The drive assembly 120 includes a guide mount 130 coupled to andsupporting the first and second guides 110, 114. The guide mount 130 isproximal of the tool sheath mount 124. The guide mount 130 permits thelongitudinal and rotational movement of the first and second guides 110,114. The guide mount 130 is slidably mounted on the track 122. The guidemount 130 includes a lower housing 132 and an upper housing 134 coupledtogether. The lower and upper housings 134 may be releasably securedtogether by fasteners 135 (e.g., bolts, set screws, etc.). The lower andupper housings 132, 134 define an opening extending there-through. Theopening is generally aligned with the longitudinal axis LA. Disposedwithin opening is a guide collar 136. The guide collar 136 is internallythreaded for reasons that will become apparent. The guide collar 136 isgenerally aligned with the longitudinal axis LA. As explained in moredetail below, the guide collar 136 guides the longitudinal androtational movement of the first guide 110 relative to the longitudinalaxis LA. The guide collar 136 is rotatably disposed within the lower andupper housings 132, 134 (e.g., the guide collar 136 can rotate about thelongitudinal axis LA). One or more bearings 137 rotatably support theguide collar 136. In the illustrated embodiment, four bearings 137 areused. The guide collar 136 may include one or more exteriorcircumferential grooves 139 which receive the bearings 137. The guidecollar 136 includes first and second locking tabs 138 used to lock orsecure the position of the guide collar relative to the lower and upperhousings 132, 134. In this embodiment, each locking tab 138 includes anopening that aligns with one of the openings 140 on the back of thelower and upper housings 132, 134 (FIG. 7) so that a retainer (notshown), such as a fastener, can extend therein to secure the position ofthe guide collar 136 relative to the lower and upper housings. Changingthe position of the guide collar 136 relative to the lower and upperhousings 132, 134 (via the openings 140) changes the direction ofcurvature (e.g., the direction of the curved trajectory) that resultswhen the first and second guides 110, 114 rotate and/or translaterelative to one another.

The drive assembly 120 also includes a guide shaft 142 disposed withinthe guide collar 136. The guide shaft 142 is externally threaded forreasons that will become apparent. The threads of the guide shaft 142rotate in generally the opposite direction as the threads of the guidecollar 136. As explained in more detail below, the guide shaft 142guides the longitudinal and rotational movement of the second guide 114relative to the longitudinal axis LA. The guide shaft 142 is generallyaligned with the longitudinal axis LA. The guide shaft 142 is rotatablydisposed within the guide collar 136 (e.g., the guide shaft 142 canrotate about the longitudinal axis LA). In this embodiment, the guideshaft 142 includes first and second locking tabs 144 used to support andsecure the position of the guide shaft relative to the lower and upperhousings 132, 134 and the guide collar 136. In this embodiment, eachlocking tab 144 includes an opening that aligns with one of the openings140 on the back of the lower and upper housings 132, 134 (FIG. 7) sothat a retainer (not shown), such as a fastener, can extend therein tosecure the position of the guide shaft 142 relative to the lower andupper housings. Preferably, the same retainers may be used to secure theguide collar 136 and guide shaft 142 relative to the lower and upperhousings 134. Changing the position of the guide shaft 142 relative tothe lower and upper housings 132, 134 (via the openings) changes thedirection of curvature (e.g., the direction of the curved trajectory)that results when the first and second guides 110, 114 rotate and/ortranslate relative to one another. In the illustrated embodiment, theguide collar 136 and guide shaft 142 are positioned relative to thelower and upper housings 132, 134 such that the curved trajectory isgenerally downward as shown in FIG. 8. However, if the guide collar 136and guide shaft 142 are rotated 180 degrees relative to the lower andupper housings 132, 134, the direction of the curved trajectory would begenerally upward (not shown). Preferably, the guide collar 136 and guideshaft 142 are rotated relative to the lower and upper housings 132, 134together.

The drive assembly 120 includes a rotation drive assembly 146 (FIGS. 16and 17) disposed between the guide shaft 142 and the guide collar 136.The rotation drive assembly 146 permits the first and second guides 110,114 to rotate relative to one another. The rotation drive assembly 146also moves the first and second guides 110, 114 together longitudinallyalong the longitudinal axis LA. The rotation drive assembly 146 includesan inner collar 148, a bearing 150 and an outer collar 152. The innercollar 148, the bearing 150 and the outer collar 152 are all alignedwith the longitudinal axis LA. The inner collar 148 is mount to theinner circumferential surface of the bearing 150 and the outer collar152 is mounted to the outer circumferential surface of the bearing. Thebearing 150 permits the inner and outer collars 148, 152 to rotaterelative to one another. The inner collar 148 is internally threaded andengages the external threads of the guide shaft 142. The outer collar152 is externally threaded and engages the internal threads of the guidecollar 136. As explained in more detail below, the engagement betweenthe threads of the inner collar 148 and the guide shaft 142 rotates theinner collar in a first direction about the longitudinal axis LA and theengagement between the threads of the outer collar 152 and the guidecollar 136 rotates the outer collar in a second direction (opposite thefirst direction) about the longitudinal axis when the rotation driveassembly 146 moves longitudinally along the longitudinal axis. Therotation drive assembly 146 includes a first carriage 156 mounted to theouter collar 152. The first carriage 156 couples to the first guide 110.Accordingly, rotation of the outer collar 152 rotates the first carriage156 which rotates the first guide 110. Likewise, translation of theouter collar 152 translates the first carriage 156 which translates thefirst guide 110 along the longitudinal axis LA. The rotation driveassembly 146 includes a second carriage 158 mounted to the inner collar148. The second carriage 158 couples to the second guide 114.Accordingly, rotation of the inner collar 148 rotates the secondcarriage 158 which rotates the second guide 114. Likewise, translationof the inner collar 148 translates the second carriage 158 whichtranslates the second guide 114 along the longitudinal axis LA. Thesecond carriage 158 is generally disposed within the first carriage 156(e.g., the radially inward of the first carriage).

The drive assembly 120 includes a push bar 160 (broadly, an actuator) todrive longitudinal movement of the tool sheath 106, and the first andsecond guides 110, 114 and the rotational movement of the first andsecond guides. In this embodiment, the longitudinal movement of thedelivery sleeve 102 is done separately, such as by manually moving thedelivery sleeve mount (broadly, an actuator) along the track 122. Thepush bar 160 is operatively coupled to the tool sheath mount 124 and therotation drive assembly 146. In the illustrated embodiment, the push bar160 extends through a slot 162 in the lower housing 132 and is coupledto the tool sheath mount 124 via the first retainer 126. The firstretainer 126 permits the push bar 160 to be selectively attached anddetached from the tool sheath mount 124. The push bar 160 is free toslide within the slot 162 (e.g., movement of the push bar does not movethe lower housing 132). The push bar 160 includes an aperture generallyaligned with the longitudinal axis LA. The drive assembly 120 includes aplunger 164 that extends through the aperture. In this manner, theplunger 164 is rotatable relative to the push bar 160. The plunger 164operatively connects the push bar 160 with the rotation drive assembly146. The plunger 164 includes first and second legs 166 which extend toand engage the rotation drive assembly 146 (specifically, the outercollar 152). In the illustrated embodiment, the outer collar 152includes channels or grooves 168 that receive the ends of the legs 166(FIGS. 16 and 17). The ends of the legs 166 may include an outstandingflange 170 or catch configured to engage a lip 172 of the outer collar152. This engagement allows the rotation drive assembly 146 to be movedproximally along the longitudinal axis LA, as discussed in more detailbelow. The plunger 164 may be releasably coupled to the rotation driveassembly 146. For example, in an insertion position (FIG. 16) theplunger 164 can move proximally away from the rotation drive assembly146. The insertion position also allows the plunger 164 to be insertedinto the channels 168 of the rotation drive assembly 146. However, in awithdrawal position (FIG. 17), the plunger 164 is coupled to therotation drive assembly 146 (e.g., the outstanding flanges 170 engagethe lips 172) such that moving the plunger 164 proximally also moves therotation drive assembly proximally. The plunger 164 is permitted to movefreely within the channels 168 and may only rotate about thelongitudinal axis LA as necessary (e.g., when contacted by one of theends of the channels).

Having an independent mount 124 for the tool sheath 106 ensures that thetool sheath will move in tandem with the first and second guides 110,114 without relying on the first and second guides to generate theforces needed to deploy it. In essence, it prevents a “dragging”behavior as the tool sheath 106 is delivered. Other configurations ofthe drive system 120 are within the scope of the present disclosure.

In one embodiment, the delivery system 100 may include several differentsets (e.g., pairs) of first and second guides 110, 114, each set havinga different pre-curved configuration. In this manner, the deliverysystem 100 may be a kit-of-parts with the surgeon selecting the guide orguides 110, 114 necessary to reach the desired target location in thesurgical site S. In other words, the surgeon selects the first and/orsecond guides 110, 114 based of their curvature and the curvature neededto reach the target location at the surgical site S. In one embodiment,the delivery system 100 may include three different sets of first andsecond guides 110, 114, each set having a different curvature.

The operation of the delivery system 100 with drive system 120 will nowbe described. In operation, the straight trajectory surgical tool isremoved after it has been used to treat as much of the surgical site Sas possible. Next, the delivery system 100 is positioned. The deliverysleeve 102, the tool sheath 106 and the first and second guides 110, 114are positioned in the subject's body (e.g., the brain B) according tothe depth of the surgical site S, using the same opening used by thestraight line surgical tool. This is done by moving the delivery sleevemount, the tool sheath mount 124 and the guide mount 130 along the track122. This positioning results in the distal end 109 of the tool sheath106 being spaced apart from the final location within the surgical siteS desired to be reached. This distance will be traversed by thetranslational movement of the tool sheath 106 described below. In thisinitial or start positioning (FIGS. 4 and 5), the first and secondguides 110, 114 are in the first configuration, such that they aregenerally straight (e.g., the longitudinal axis LA is straight) (FIGS. 4and 5). With the delivery system 100 in the start position, the toolsheath 106 is ready to be advanced to the target location at thesurgical site S (FIG. 12A). Before the delivery system 100 is moved tothis start position, the surgeon may rotate and set the guide collar 136and guide shaft 142 relative to the lower and upper housings 132, 134using the openings 140 to set the direction of curvature imparted by thefirst and second guides 110, 114.

To advance the tool sheath 106 to the target location at the surgicalsite S, the delivery system 100 is moved to an end position (FIGS. 6-8).Specifically, the surgeon engages the push bar 160 and moves the pushbar distally. As the push bar 160 is moved distally, the push bar movesthe tool sheath mount 124 distally, thereby moving the tool sheath 106toward the target location at the surgical site S (FIG. 12B). At thesame time, the push bar 160 pushes the plunger 164 distally. This movesthe first and second guides 110, 114 distally and rotates the first andsecond guides relative to one another, simultaneously, and with thedistal movement of the tool sheath 106. As the push bar 160 pushes theplunger 164 distally, the plunger pushes the rotation drive assembly 146distally along the guide collar 136 and guide shaft 142. The guidecollar 136, guide shaft 142, and lower and upper housings 132, 134 arefixed in position on the track 122 and do not move with the push bar160. As the plunger 164 pushes the rotation drive assembly 146 distally,the first and second guides 110, 114 move distally along thelongitudinal axis LA (FIG. 12B) and rotate about the longitudinal axisLA simultaneously. As the outer collar 152 moves distally, the exteriorthreads of the outer collar engage the internal threads of the guidecollar 136, thereby causing the outer collar to rotate in one direction.Likewise, as the inner collar 148 moves distally, the interior thread ofthe inner collar engage the external thread of the guide shaft 142,thereby causing the inner collar to rotate in the other direction. Inone embodiment, the inner and outer collars 148, 152 (e.g., first andsecond guides 110, 114) each rotate about 90 degrees (in oppositedirections) about the longitudinal axis LA as the rotation driveassembly 146 is moved from the start position to the end position. Thisresults in the first and second guides 110, 114 rotating about 180degrees relative to one another such that in the end position, the firstand second guides are positioned to have the maximum degree of curvaturein the second configuration. As the first and second guides 110, 114rotate relative to one another (and as they are advanced distally), thefirst and second guides 110, 114 begin to curve (e.g., return to theirnatural pre-curved state), thereby curving the tool sheath 106 (e.g.,the longitudinal axis LA). This creates a curved trajectory that thetool sheath 106 and first and second guides 110, 114 continue to followuntil they reach the end position. Accordingly, as the first and secondguides 110, 114 move longitudinally along the longitudinal axis LA, thefirst and second guides curve toward the desired location at thesurgical site S, thereby guiding the tool sheath 106 to the desiredlocation. In one embodiment, the distal end 109 of the tool sheath 106is disposed at the desired location in the surgical site S when thedelivery system 100 is in the end position. In another embodiment, thetool sheath 106 and the first and second guides 110, 114 may continue tobe advanced distally (along the now defined curved trajectory) toposition the distal end 109 of the tool sheath at the desired location.In this embodiment, the first and second guides 110, 114 would stoprotating once they reached the end position (e.g., the guide mount 130and tool sheath mount 124 would be advanced distally along the track122).

Once the distal end 109 of the tool sheath 106 is positioned in thesurgical site S, the tool sheath 106 is secured in place on the track122. The surgeon uses the first retainer 126 to disconnect the push bar160 from the tool sheath mount 124 and secure the tool sheath mount inposition on the tract 122. The surgeon then places the plunger 164 in awithdrawal position (FIG. 17) such that the outstanding flanges 170engage the lips 172 of the rotation drive assembly 146. In thisposition, moving the plunger 164 proximally, moves the rotation driveassembly 146 proximally. As the rotation drive assembly 146 movesproximally, the inner and outer collars 148, 152 (e.g., the first andsecond guides 110, 114) rotate back toward the first configuration. Thisallows the first and second guides 110, 114 to withdraw from the toolsheath 106 without affecting the curved shape the first and secondguides imparted on the tool sheath. Once in the start position, theguide mount 130 may be removed from the track 122 to remove the firstand second guides 110, 114, thereby leaving the tool sheath 106 at thesurgical site S (FIGS. 9 and 12C). At this point, a surgical tool T maybe inserted through the tool sheath 106 to treat the formerly out ofreach locations within the surgical site S (FIG. 19) (e.g., reachoff-axis targets).

To retract the tool sheath 106 after the treatment, the first and secondguides 110, 114 are inserted back into the tool sheath in the samemanner described above in relation to positioning the tool sheath. Onceat the end position, the push bar 160 is then reconnected to the toolsheath mount 124. The plunger 164 is moved proximally to withdrawn thetool sheath 106 and first and second guides 110, 114 back to the startposition. Again in this position, the longitudinal axis LA is generallystraight. This allows the tool sheath 106 to be withdrawn from thesurgical site S along the same trajectory the tool sheath was movedtoward the surgical site, minimizing any damage to the surroundingtissue. Once back the start position, the entire delivery system 100 maythen be removed from the subject. At this point, a surgeon can changethe direction of curvature by rotating the guide shaft 142 and guidecollar 136 relative to the lower and upper housings 132, 134 and settingthe new orientation using the holes 140 to restart the process again anddirect the tool sheath to a different target location within thesurgical site S. For example, by repeating this process, the surgeon canreach different locations L1, L2, L3 (L2 and L3 are shown in dashedlines in FIG. 19) within a surgical site S.

Generally speaking, one embodiment of a method for accessing a surgicalsite S (e.g., a location with a subject's brain B) includes advancing adistal end of the delivery system, as described herein (i.e., deliverysystem 100) through the body tissue of a subject to position the distalend of the delivery system in the body tissue and a proximal end of thedelivery system outside the body tissue. The delivery system 100 guidesa surgical tool T to the surgical site S. The method includes guidingthe distal end of the delivery system 100 to the surgical site S bylongitudinally moving the first guide 110 and the tool sheath 106relative to the delivery sleeve 102. The method further includesretracting the first guide 110 proximally through the tool sheath 106such that the distal end of the delivery system 100 is defined by thedistal end 109 of the tool sheath 106.

Moving the first guide 110 relative to the delivery sleeve 102 may movethe distal end of the delivery system 100 out of alignment with thestraight longitudinal axis LA (e.g., off axis). This allows the distalend of the delivery system 100 to be positioned closer to a desiredlocation within the surgical site S. In one embodiment, the first guide110 is moved distally relative to the delivery sleeve 102. The firstguide 110 is deformable and has a generally curved shape in itsundeformed state. At least a portion of the first guide 110 is curvedwhen the first guide is moved distally relative to the delivery sleeve102. In particular, the portion of the first guide 110 distal of thedelivery sleeve 102 is no longer constrained (e.g., deformed) by thedelivery sleeve and returns to its curved or undeformed state. In oneembodiment, the first guide 110 and the tool sheath 106 are movedtogether.

The method may further include removing the first guide 110 from thetool sheath 106. In other words, the method may further include removingany components containing Nitinol or other imaging interfering materialsfrom the distal end of the delivery system 110. The method may alsoinclude advancing a surgical tool T distally though the tool sheath 106to position the surgical tool at the desired location at the surgicalsite S. The method may also include imaging the surgical site S todetermine the position of the distal end 109 of the tool sheath 106relative to the surgical site after the first guide 110 has beenretracted. As a result of removing the first guide 110 from the toolsheath 106, any images taken of the surgical site S during the surgicalprocedure showing the position of the surgical tool T relative to thesurgical site are clear and unobstructed by the delivery system 100(specifically the tool sheath).

The method may include using a delivery system 100 having a second guide114 movably disposed longitudinally within the first guide 110 such thatguiding the distal end of the delivery system to the surgical site Sincludes longitudinally moving the first and second guides relative tothe delivery sleeve 102. The first and second guides 110, 114 may bemoved together relative to the delivery sleeve 102. Additionally oralternatively, the first and second guides 110, 114 may be movedlongitudinally relative to one another. Additionally or alternatively,the first and second guides 110, 114 may be rotated relative to oneanother when guiding the distal end of the delivery system 100.Accordingly, due to the curves of the first and second guides 110, 114and the ability to position the curves of the first and second guidesrelative to one another, as described herein, moving the first andsecond guides together relative to the delivery sleeve 102 either movesthe distal end of the delivery system 100 out of alignment with thelongitudinal axis LA or moves the distal end of the delivery systemalong the longitudinal axis.

An important component of the above delivery system 100 is the toolsheath 106. The tool sheath 106 must be flexible enough to be shaped byand follow the first and second guides 110, 114, but rigid enough tomaintain its shape when sitting in brain tissue once the first andsecond guides are removed. For example, the tool sheath 106 may behavingsimilar to a flexible straw embedded in gelatin. Because of theflexibility and cushion of the surrounding environment, the tool sheath106 placement and configuration by the first and/or second guides 110,114 and the maintaining of the tool sheath placement and configurationafter the first and second guides are retracted is achieved.

Other embodiments of the delivery system are within the scope of thepresent disclosure. For example, in one alternative embodiment, adelivery system (not shown) may not include the delivery sleeve 102 andthe tool sheath 106 but otherwise is generally similar to deliverysystem 100. In this embodiment, the delivery system includes the firstand second guides 110, 114, with the second guide 114 defining a secondguide lumen 115 (FIG. 10) sized and shaped to receive the surgical toolT. In other words, in this embodiment, the first and second guides 110,114 form the tool sheath which guides the surgical tool T to the desiredlocation at the surgical site S. In this embodiment, the first andsecond guides 110, 114 are preferably made out of a material that doesnot interfere with the imaging of the surgical site S but still has thesuper elasticity required to form the different trajectories (e.g.,curved and straight). This way, the first and second guides 110, 114 canremain at the surgical site S and guide the surgical tool T to thedesired location while not interfering with the imaging of the surgicalsite. For example, the first and second guides 110, 114 can be made ofone or more polymers that do not interfere with the imaging of thesurgical site S but still provide the necessary elasticity. For example,polymers include polyamides, such as synthetic polyamides (e.g., variousnylons including nylon 6,6 and nylon 6), polyvinyl chloride (PVC),polycaprolactone (PCL), polydioxanone (PDO), or a fluoropolymer.Fluoropolymers include, for example, polytetrafluoroethylene (PTFE),fluorinated ethylene-propylene (FEP), perfluoroalkoxy resin (PFE, acopolymer of tetrafluoroethylene and perfluorovinylethers),ethylene-tetrafluoroethylene copolymer (ETFE),polychlorotrifluoroethylene (PCTFE), ethylene-chloro-trifluoroethylenecopolymer (ECTFE), polyvinylidene fluoride (PVDF), and polyvinylfluoride (PVF). Preferably the fluoropolymer is PTFE. In one embodiment,the first and second guides 110, 114 are formed by electrospinning thebiocompatible polymer. Otherwise, the first and second guides 110, 114are generally the same as described above (hence the same referencenumbers) and operate in the same way.

In this embodiment, the delivery system without the delivery sleeve andtool sheath may also include any drive system described herein, such asdrive system 120. In this case the drive system would still include theguide mount 130 and the plunger 164 (and possibly the push rod 160),which are generally need to translate and rotate the first and secondguides 110, 114 relative to the longitudinal axis LA. However, the drivesystem would not include the delivery sleeve mount and the tool sheathmount. In addition, the drive system may include first and second guidemounts (not shown) to secure the first and second guides 110, 114 inposition. The first and second guide mounts may be generally the same asthe tool sheath mount 124 described above. The first and second guidemounts would secure the first and second guides 110, 114 in position,when the first and second guides are in the end position and/or secondconfiguration, to allow the guide mount 130 to be disconnected from thefirst and second guides to permit the surgical tool T to be entered intothe second guide lumen 115. Other configurations are within the scope ofthe present disclosure.

This embodiment of the delivery system would operate in a similar mannerto delivery system 100 except without the delivery sleeve and toolsheath. For example, in general, one method for accessing the surgicalsite S using this delivery system includes advancing a distal end of thedelivery system through the body tissue of a subject to position thedistal end of the delivery system in the body tissue and a proximal endof the delivery system outside the body tissue. In this embodiment, thedistal end of the delivery system is defined by the distal end of thesecond guide 114 and/or first guide 110. The method includes guiding thedistal end of the first and/or second guide 110, 114 to the surgicalsite S by longitudinally moving the first and second guides 110, 114along the longitudinal axis LA and rotating the first and second guidesabout the longitudinal axis. Rotating the first and second guides 110,114 relative to one another moves the distal end of the first and/orsecond guide out of alignment with the straight longitudinal axis LA (asdescribed above). In other words, as described above, rotating the firstand second guides 110, 114 relative to one another creates the curvedtrajectory used to guide the first and second guides to the desiredlocation at the surgical site S. Due to the curves of the first andsecond guides 110, 114 and the ability to position the curves of thefirst and second guides relative to one another, as described herein,rotating the first and second guides together relative to one anothercan result in the longitudinal axis LA having a first shape (e.g.,straight shape) with the guides in the first configuration and adifferent second shape (e.g., curved shape) with the guides in thesecond configuration. The method further includes inserting a surgicaltool T through the lumen 115 of the second guide 114 to apply treatmentat the surgical site, after the first and second guides 110, 114 havebeen positioned. The method may further include imaging the surgicalsite S to ensure the surgical tool T is properly positioned. The methodmay further include retracting the first and second guides 110, 114 fromthe surgical site S after the treatment is completed with the surgicaltool T (and the surgical tool is withdrawn). Withdrawing the first andsecond guides 110, 114 may include moving the guides proximally whilethe guides rotate back to their start positions (e.g., rotate back to astraight line trajectory), for reasons described herein. This processcan then be repeated for different locations within the surgical site Sby resetting the direction of curvature of the first and second guides110, 114 as described herein.

Embodiments of a method of performing a surgical procedure in asubject's brain comprise accessing the surgical site within thesubject's brain according any of the methods described herein; advancinga surgical tool distally though the tool sheath to position the surgicaltool at the surgical site; and operating the surgical tool. In variousembodiments, the surgical tool comprises an ablation tool such as alaser ablation tool (e.g., a laser ablation tool suitable for LITT).

The methods of the present disclosure can be used for a wide range ofsubjects. In various embodiments, the subject is a mammal (e.g., ahuman).

The delivery systems and methods described herein are suitable to serveas a “touch-up” procedure for existing procedures using straighttrajectories initially to treat the majority of the surgical site S.When the curved path is needed, the surgeon uses the delivery systemsdescribed herein with the existing straight yet flexible surgical toolsT to steer to desired off-axis locations. However, it is understood thedelivery system and methods described herein may also be used as themain procedure (e.g., straight line procedure) as well.

Example

The following is a non-limiting example to further illustrate thepresent disclosure.

In one experiment, four mock tumors were placed in 12 off-axis locationswithin a 10% by weight Knox-Gelatin phantom tissue model. The tumorswere placed at 4 cm, 6 cm, and 8 cm in depth from the entry point of thedelivery system. For each tumor, the delivery system according to thepresent disclosure was used. The PTFE port was deployed, the cannulasystem was retracted, and an existing LITT probe was delivered throughthe port to a targeted tumor. Of the 12 tumors tested, the port wasdelivered deployed successfully 12 times, the cannula system wasretracted successfully 11 times, and the LITT probe was deliveredthrough the port successfully 10 times. While these results arequalitative, they illustrate the feasibility of the delivery system.

Having described the disclosure in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the disclosure defined in the appended claims. For example,where specific dimensions are given, it is understood these dimensionsare exemplary and other dimensions are possible.

When introducing elements of the present disclosure or the preferredembodiments(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of thedisclosure are achieved and other advantageous results attained.

As various changes could be made in the above systems and methodswithout departing from the scope of the disclosure, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

1. A method for accessing a surgical site in a subject, the methodcomprising: advancing a distal end of a delivery system through bodytissue of the subject to position the distal end of the delivery systemin the body tissue and a proximal end of the delivery system outside thebody tissue, the delivery system configured to guide a surgical tool tothe surgical site, the delivery system including a delivery sleevehaving a longitudinal axis extending between proximal and distal ends ofthe delivery system, a tool sheath movably disposed longitudinallywithin the delivery sleeve, and a first guide movably disposedlongitudinally within the tool sheath; guiding the distal end of thedelivery system to the surgical site by longitudinally moving the firstguide and the tool sheath relative to the delivery sleeve; andretracting the first guide proximally through the tool sheath such thatthe distal end of the delivery system is defined by the distal end ofthe tool sheath.
 2. The method of claim 1, wherein moving the firstguide relative to the delivery sleeve moves the distal end of thedelivery system out of alignment with the longitudinal axis.
 3. Themethod of claim 1 or 2, wherein the first guide is moved distallyrelative to the delivery sleeve.
 4. The method of any one of claims 1-3,wherein the first guide is deformable and has a generally curved shapein an undeformed state.
 5. The method of any one of claims 1-4, whereinat least a portion of the first guide is curved when the first guide ismoved distally relative to the delivery sleeve.
 6. The method of any oneof claims 1-5, wherein the first guide and the tool sheath are movedtogether.
 7. The method of any one of claims 1-6, further comprisingimaging the surgical site to determine the position of the distal end ofthe tool sheath relative to the surgical site after the first guide hasbeen retracted.
 8. The method of any one of claims 1-7, furthercomprising removing the first guide from the tool sheath.
 9. The methodof any one of claims 1-8, further comprising advancing a surgical tooldistally though the tool sheath to position the surgical tool at thesurgical site.
 10. The method of any one of claims 1-9, wherein thedelivery system further includes a second guide movably disposedlongitudinally within the first guide and guiding the distal end of thedelivery system to the surgical site includes longitudinally moving thefirst and second guides relative to the delivery sleeve.
 11. The methodof claim 10, wherein the first and second guides are moved togetherrelative to the delivery sleeve.
 12. The method of claim 10 or 11,wherein guiding the distal end of the delivery system includeslongitudinally moving the first and second guides relative to oneanother.
 13. The method of any one of claims 10-12, wherein guiding thedistal end of the delivery system includes rotating the first and secondguides relative to one another.
 14. The method of any one of claims10-13, wherein the first and second guides are deformable and have agenerally curved shape in an undeformed state.
 15. The method of any oneof claims 10-14, wherein moving the first and second guides togetherrelative to the delivery sleeve either moves the distal end of thedelivery system out of alignment with the longitudinal axis or moves thedistal end of the delivery system along the longitudinal axis.
 16. Themethod of any one of claims 10-15, wherein the second guide comprises anickel-titanium shape memory alloy.
 17. The method of any one of claims10-15, wherein the second guide comprises a polymer.
 18. The method ofclaim 17, wherein the polymer is selected from the group consisting ofpolyamides, synthetic polyamides, nylons, nylon 6,6, nylon 6, polyvinylchloride (PVC), polycaprolactone (PCL), polydioxanone (PDO),fluoropolymers, and combinations thereof.
 19. The method of claim 17 or18, wherein the polymer comprises a fluoropolymer.
 20. The method ofclaim 18 or 19, wherein the fluoropolymer is selected from the groupconsisting of polytetrafluoroethylene (PTFE), fluorinatedethylene-propylene (FEP), perfluoroalkoxy resin (PFE, a copolymer oftetrafluoroethylene and perfluorovinylethers),ethylene-tetrafluoroethylene copolymer (ETFE),polychlorotrifluoroethylene (PCTFE), ethylene-chloro-trifluoroethylenecopolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride(PVF), and combinations thereof.
 21. The method of any one of claims18-20, wherein the fluoropolymer comprises polytetrafluoroethylene(PTFE).
 22. The method of any one of claims 1-21, wherein the firstguide comprises a nickel-titanium shape memory alloy.
 23. The method ofany one of claims 1-21, wherein the first guide comprises a polymer. 24.The method of claim 23, wherein the polymer is selected from the groupconsisting of polyamides, synthetic polyamides, nylons, nylon 6,6, nylon6, polyvinyl chloride (PVC), polycaprolactone (PCL), polydioxanone(PDO), fluoropolymers, and combinations thereof.
 25. The method of claim23 or 24, wherein the polymer comprises a fluoropolymer.
 26. The methodof claim 24 or 25, wherein the fluoropolymer is selected from the groupconsisting of polytetrafluoroethylene (PTFE), fluorinatedethylene-propylene (FEP), perfluoroalkoxy resin (PFE, a copolymer oftetrafluoroethylene and perfluorovinylethers),ethylene-tetrafluoroethylene copolymer (ETFE),polychlorotrifluoroethylene (PCTFE), ethylene-chloro-trifluoroethylenecopolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride(PVF), and combinations thereof.
 27. The method of any one of claims24-26, wherein the fluoropolymer comprises polytetrafluoroethylene(PTFE).
 28. The method of any one of claims 1-27, wherein the surgicalsite is a location within the subject's brain.
 29. The method of any oneof claims 1-28, wherein the tool sheath is a constructed of a polymer.30. The method of claim 29, wherein the polymer is selected from thegroup consisting of polyamides, synthetic polyamides, nylons, nylon 6,6,nylon 6, polyvinyl chloride (PVC), polycaprolactone (PCL), polydioxanone(PDO), fluoropolymers, and combinations thereof.
 31. The method of claim29 or 30, wherein the polymer comprises a fluoropolymer.
 32. The methodof claim 30 or 31, wherein the fluoropolymer is selected from the groupconsisting of polytetrafluoroethylene (PTFE), fluorinatedethylene-propylene (FEP), perfluoroalkoxy resin (PFE, a copolymer oftetrafluoroethylene and perfluorovinylethers),ethylene-tetrafluoroethylene copolymer (ETFE),polychlorotrifluoroethylene (PCTFE), ethylene-chloro-trifluoroethylenecopolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride(PVF), and combinations thereof.
 33. The method of any one of claims30-32, wherein the fluoropolymer comprises polytetrafluoroethylene(PTFE).
 34. The method of any one of claims 1-33, further comprising anactuator operatively coupled to the tool sheath and the first guide,wherein the actuator drives movement of the tool sheath and the firstguide.
 35. The method of any one of claims 1-33, further comprising afirst actuator operatively coupled to the tool sheath and a secondactuator operatively coupled to the first guide, wherein the firstactuator drives movement of the tool sheath and the second actuatordrives movement of the first guide.
 36. A method of performing asurgical procedure in a subject's brain, the method comprising:accessing the surgical site within the subject's brain according to themethod of any one of claims 1-33; advancing a surgical tool distallythough the tool sheath to position the surgical tool at the surgicalsite; and operating the surgical tool.
 37. The method of claim 36,wherein the surgical tool comprises an ablation tool.
 38. The method ofclaim 36 or 37, wherein the surgical tool comprises a laser ablationtool.
 39. The method of any one of claims 35-37, wherein the surgicalprocedure is laser interstitial thermal therapy for brain tumors. 40.The method of any one of claims 1-39, wherein the subject is a mammal.41. The method of any one of claims 1-40, wherein the subject is ahuman.
 42. A delivery system for guiding a surgical tool to a surgicalsite, the delivery system comprising: a delivery sleeve having alongitudinal axis and proximal and distal ends spaced apart from oneanother along the longitudinal axis, the delivery sleeve configured tobe inserted into the body tissue of a subject; a tool sheath movablydisposed longitudinally within the delivery sleeve, the tool sheathdefining a lumen configured to receive the surgical tool; and a firstguide movably disposed longitudinally in the lumen of the tool sheath,the first guide being deformable and having a generally curved shapewhen the first guide is not deformed; wherein the first guide and toolsheath are configured to be moved distal of the delivery sleeve so thatthe first guide can guide a distal end of the tool sheath to thesurgical site; wherein the first guide is deformed when the first guideis disposed within the delivery sleeve and at least a portion of thefirst guide has a generally curved shape when the first guide is moveddistally through the distal end of the delivery sleeve; and wherein thetool sheath is flexible and generally conforms to the shape of the firstguide.
 43. The delivery system of claim 42, further comprising a secondguide movably disposed longitudinally within the first guide, the secondguide being deformable and having a generally curved shape when thesecond guide is not deformed; wherein the first and second guides andtool sheath are configured to be moved distal of the delivery sleeve sothat the first and second guides can guide the distal end of the toolsheath to the surgical site; wherein the second guide is deformed whenthe second guide is disposed within the delivery sleeve; wherein thefirst and second guides are configured to move at least one oflongitudinally and rotationally relative to one another to change therelative shapes of the first and second guides; and wherein the toolsheath generally conforms to the shapes of the first and second guides.44. The delivery system of claim 42 or 43, wherein the first guide isconfigured to be removed from the lumen of the tool sheath to permit thesurgical tool to be inserted into the lumen.
 45. The delivery system ofany one of claims 42-44, further comprising a drive assembly operativelyconnected to the delivery sleeve, the tool sheath and the first guideand configured to move the delivery sleeve, the tool sheath and thefirst guide into the body tissue of the subject.
 46. The delivery systemof claim 45, wherein the drive assembly is configured to move thedelivery sleeve, the tool sheath and the first guide together and moveeach of the delivery sleeve, the tool sheath and the first guiderelative to one another.
 47. The delivery system of claim 45 or 46,wherein the drive assembly is configured to rotate the first guiderelative to the delivery sleeve and the tool sheath.
 48. A deliverysystem for guiding a surgical tool to a surgical site, the deliverysystem comprising: a first guide having a longitudinal axis and proximaland distal ends spaced apart from one another along the longitudinalaxis, the first guide configured to be inserted into the body tissue ofa subject, the first guide defining a lumen extending between theproximal and distal ends, the first guide being deformable and having agenerally curved shape when the first guide is not deformed; a secondguide movably disposed in the lumen of the first guide, the second guidebeing deformable and having a generally curved shape when the secondguide is not deformed; wherein the longitudinal axis has a first shapewhen the first and second guides are disposed relative to one another ina first configuration and a second shape different than the first shapewhen the first and second guides are disposed relative to one another ina second configuration.
 49. The delivery system of claim 48, wherein thelongitudinal axis is generally straight when the first and second guidesare in the first configuration and wherein at least a portion of thelongitudinal axis is curved when the first and second guides are in thesecond configuration.
 50. The delivery system of claim 48 or 49, furthercomprising a tool sheath defining a tool sheath lumen, wherein the firstand second guides are movably disposed within the tool sheath lumen,wherein the tool sheath is flexible and generally conforms to the shapeof the first and second guides.
 51. The delivery system of claim 50,wherein the tool sheath lumen is sized and shaped to receive thesurgical tool.
 52. The delivery system of any one of claims 48-51,wherein the second guide defines a second guide lumen sized and shapedto receive the surgical tool.
 53. The delivery system of any one ofclaims 48-52, further comprising a drive assembly operatively coupled tothe first and second guides, the drive assembly configured to move thefirst and second guides simultaneously.
 54. The delivery system of claim53, wherein the drive assembly is configured to move the first andsecond guides independently of one another.
 55. The delivery system ofclaim 53 or 54, wherein the drive assembly is configured to move thefirst and second guides along the longitudinal axis.
 56. The deliverysystem of any one of claims 53-55, wherein the drive assembly isconfigured to rotate the first and second guides about the longitudinalaxis.